• 原理解釋

@Cacheable註解作用，將帶有該註解方法的返回值存放到redis中；

使用方法在方法上使用@Cacheable(key=”test+#p0+#p1....”)

表示key值為test+方法第一個引數+方法第二個引數，value值為該方法的返回值。

以下源程式碼表示獲取人員列表，redis中存放的key值為‘leader’+leaderGroupId+uuid+yearDetailId

        @Override
	@Cacheable(key="'leader'+#p0+#p1+#p2",value="leader")
	public List<Leader> listLeaders(String leaderGroupId, String uuid, String yearDetailId) {
		return sysIndexMapper.listLeaders(leaderGroupId, uuid, yearDetailId);
	}
 

等同於

        @Override
	public List<Leader> listLeaders(String leaderGroupId, String uuid, String yearDetailId) {
		String key = "leader" + leaderGroupId + uuid + yearDetailId;
		// 判斷快取是否存在redis中
		boolean hasKey = redisUtil.hasKey(key);
		if (hasKey) {
                        //如果存在 返還redis中的值
			Object leadersList = redisUtil.get(key);
			return (List<Leader>) leadersList;
		} else {
			List<Leader> leadersQuotaDetailList = sysIndexMapper.listLeaders(leaderGroupId, uuid, yearDetailId);
                        //將查詢結果存放在redis中
			redisUtil.set(key, leadersQuotaDetailList);
			return leadersQuotaDetailList;
		}
	}
 

說白了就是在原方法的前面判斷key值是否存在redis中，如果存在就取記憶體中的值，如果不存在就查詢資料庫，將查詢結果存放在redis中。

• 實現方法

1. 使用代理模式，在方法執行前和執行後可以新增其他處理程式，本文采用springAOP+註解方式。
2. 整合redis,封裝redis工具類
3. 原版本不支援key過期時間設定，本文將實現

• 原始碼

快取配置類 RedisConfig

package com.huajie.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.CachingConfigurerSupport;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * Redis快取配置類
 */
@Configuration
@EnableCaching
public class RedisConfig extends CachingConfigurerSupport {

	@Value("${spring.redis.host}")
	private String host;
	@Value("${spring.redis.port}")
	private int port;
	@Value("${spring.redis.timeout}")
	private int timeout;

	// 自定義快取key生成策略
	@Bean
	public KeyGenerator keyGenerator() {
		return new KeyGenerator() {
			@Override
			public Object generate(Object target, java.lang.reflect.Method method, Object... params) {
				StringBuffer sb = new StringBuffer();
				sb.append(target.getClass().getName());
				sb.append(method.getName());
				for (Object obj : params) {
					sb.append(obj.toString());
				}
				return sb.toString();
			}
		};
	}

	// 快取管理器
	@Bean
	public CacheManager cacheManager(@SuppressWarnings("rawtypes") RedisTemplate redisTemplate) {
		RedisCacheManager cacheManager = new RedisCacheManager(redisTemplate);
		// 設定快取過期時間
		cacheManager.setDefaultExpiration(10000);
		return cacheManager;
	}

	@Bean
	public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
		RedisTemplate<String, Object> template = new RedisTemplate<String, Object>();
		template.setConnectionFactory(factory);
		Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
		ObjectMapper om = new ObjectMapper();
		om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
		om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
		jackson2JsonRedisSerializer.setObjectMapper(om);
		StringRedisSerializer stringRedisSerializer = new StringRedisSerializer();
		// key採用String的序列化方式
		template.setKeySerializer(stringRedisSerializer);
		// hash的key也採用String的序列化方式
		template.setHashKeySerializer(stringRedisSerializer);
		// value序列化方式採用jackson
		template.setValueSerializer(jackson2JsonRedisSerializer);
		// hash的value序列化方式採用jackson
		template.setHashValueSerializer(jackson2JsonRedisSerializer);
		template.afterPropertiesSet();
		return template;
	}

	private void setSerializer(StringRedisTemplate template) {
		@SuppressWarnings({ "rawtypes", "unchecked" })
		Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
		ObjectMapper om = new ObjectMapper();
		om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
		om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
		jackson2JsonRedisSerializer.setObjectMapper(om);
		template.setValueSerializer(jackson2JsonRedisSerializer);
	}
}
 

redis依賴引入，配置檔案，工具類RedisUtil ，網上幾個版本都類似，本文參考以下版本傳送門

準備工作做好之後開始正式編寫註解@Cacheable nextkey()用做二級快取 本文中不會用到

建立java註解@ExtCacheable  

package com.huajie.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
public @interface ExtCacheable {
	
	String key() default "";
	
	String nextKey() default "";

	int expireTime() default 1800;//30分鐘
	
}

SpringAop切面 CacheableAspect

package com.huajie.aspect;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import com.huajie.annotation.ExtCacheable;
import com.huajie.utils.RedisUtil;

/**
 * redis快取處理
 * 不適用與內部方法呼叫(this.)或者private
 */
@Component
@Aspect
public class CacheableAspect {
	
	@Autowired
	private RedisUtil redisUtil;

	@Pointcut("@annotation(com.huajie.annotation.ExtCacheable)")
	public void annotationPointcut() {
	}

	@Around("annotationPointcut()")
	public Object doAround(ProceedingJoinPoint joinPoint) throws Throwable {
		// 獲得當前訪問的class
		Class<?> className = joinPoint.getTarget().getClass();
		// 獲得訪問的方法名
		String methodName = joinPoint.getSignature().getName();
		// 得到方法的引數的型別
		Class<?>[] argClass = ((MethodSignature) joinPoint.getSignature()).getParameterTypes();
		Object[] args = joinPoint.getArgs();
		String key = "";
		int expireTime = 1800;
		try {
			// 得到訪問的方法物件
			Method method = className.getMethod(methodName, argClass);
			method.setAccessible(true);
			// 判斷是否存在@ExtCacheable註解
			if (method.isAnnotationPresent(ExtCacheable.class)) {
				ExtCacheable annotation = method.getAnnotation(ExtCacheable.class);
				key = getRedisKey(args,annotation);
				expireTime = getExpireTime(annotation);
			}
		} catch (Exception e) {
			throw new RuntimeException("redis快取註解引數異常", e);
		}
		// 獲取快取是否存在
		boolean hasKey = redisUtil.hasKey(key);
		if (hasKey) {
			return redisUtil.get(key);
		} else {
                         //執行原方法（java反射執行method獲取結果）
			Object res = joinPoint.proceed();
                         //設定快取
			redisUtil.set(key, res);
                         //設定過期時間
			redisUtil.expire(key, expireTime);
			return res;
		}
	}
	
	private int getExpireTime(ExtCacheable annotation) {
		return annotation.expireTime();
	}

	private String getRedisKey(Object[] args,ExtCacheable annotation) {
		String primalKey = annotation.key();
		//獲取#p0...集合
		List<String> keyList = getKeyParsList(primalKey);
		for (String keyName : keyList) {
			int keyIndex = Integer.parseInt(keyName.toLowerCase().replace("#p", ""));
			Object parValue = args[keyIndex];
			primalKey = primalKey.replace(keyName, String.valueOf(parValue));
		}
		return primalKey.replace("+","").replace("'","");
	}

	// 獲取key中#p0中的引數名稱
	private static List<String> getKeyParsList(String key) {
		List<String> ListPar = new ArrayList<String>();
		if (key.indexOf("#") >= 0) {
			int plusIndex = key.substring(key.indexOf("#")).indexOf("+");
			int indexNext = 0;
			String parName = "";
			int indexPre = key.indexOf("#");
			if(plusIndex>0){
				indexNext = key.indexOf("#") + key.substring(key.indexOf("#")).indexOf("+");
				parName = key.substring(indexPre, indexNext);
			}else{
				parName = key.substring(indexPre);
			}
			ListPar.add(parName.trim());
			key = key.substring(indexNext + 1);
			if (key.indexOf("#") >= 0) {
				ListPar.addAll(getKeyParsList(key));
			}
		}
		return ListPar;
	}
	
}

業務模組使用方法

@Override
	@ExtCacheable(key = "Leaders+#p0+#p1+#p2")
	// 手機端獲取領導人員列表
	public List<Leader> listLeaders(String leaderGroupId, String uuid, String yearDetailId) {
		List<Leader> leadersQuotaDetailList = sysIndexMapper.listLeaders(leaderGroupId, uuid, yearDetailId);
		return leadersQuotaDetailList;
	}

業務模組過期時間使用方法，5分鐘過期

@Override
	@ExtCacheable(key = "mobileCacheFlag", expireTime = 60 * 5)
	public int cacheFlag() {
		int mobileCacheFlag = 1;
		mobileCacheFlag = sysIndexMapper.cacheFlag();
		return mobileCacheFlag;
	}

redis截圖